Well Deployed Heat Fin For ESP Motor

ABSTRACT

An electrical submersible pumping system (ESP) for use in pumping fluids from a wellbore. The ESP includes fins on an outer portion of the ESP that transfer heat from a motor in the ESP to fluid flowing past the fins. A self removing material is provided over the fins when the ESP is deployed into the wellbore to protect the fins against being damaged when the ESP contacts a wall of the wellbore. The material can corrode, erode, melt, dissolve, disintegrate, or otherwise automatically decouple from the fins when the ESP is disposed in the wellbore.

BACKGROUND

1. Field of Invention

The present disclosure relates to electrical submersible pumping (ESP)systems submersible in well bore fluids. More specifically, the presentdisclosure concerns a method of protecting motor cooling fins duringdeployment of an ESP.

2. Description of Prior Art

Submersible pumping systems are often used in hydrocarbon producingwells for pumping fluids from within the well bore to the surface. Thesefluids are generally liquids and include produced liquid hydrocarbon aswell as water. One type of system used in this application employs anelectrical submersible pump (ESP). ESP's are typically disposed at theend of a length of production tubing and have an electrically poweredmotor. Often, electrical power may be supplied to the pump motor via anelectrical cable. Typically, the pumping unit is disposed within thewell bore above where perforations are made into a hydrocarbon producingzone. This placement thereby allows the produced fluids to flow past theouter surface of the pumping motor and provide a cooling effect. Themotor may become overheated without the cooling effect by the transferof heat. The prospect of overheating, even while heat is beingtransferred to fluid flowing adjacent the motor, limits the pumpingability of an ESP.

SUMMARY OF INVENTION

The present disclosure describes an electrical submersible pumpingsystem (ESP) with an improved cooling system and a method of cooling anESP. In an example embodiment, disclosed is a method of cooling an ESPthat involves adding fins to an outer surface of the ESP. The fins areshielded from damage by covering or potting them with a protectivelayer(s) that is removed after the ESP is deployed within a wellbore.While the ESP is being lowered downhole and inadvertently contacts awall of the wellbore, the protective layer(s) safeguards the fins fromdamage. In an example embodiment, the potting or shielding materialdisintegrates when disposed in a wellbore and the fins conduct heat fromwithin the ESP to fluid in the wellbore. The material can be made fromwax, aluminum, zinc, beryllium, magnesium, alloys thereof, andcombinations thereof. Optionally, the covering can be a protectivepacking encapsulated with an outer layer. Where in this example, theprotective packing can be particulate material, sand, plaster, wax, andcombinations thereof and the outer layer can be aluminum, zinc,beryllium, magnesium, alloys thereof, or combinations thereof. In anexample embodiment, the fins are disposed on a motor section of the ESPthat contains a motor for driving a pump in the ESP. After deploying theESP with the protected fins, the motor can be started to drive the pump,and fluid can be pumped from the wellbore into production tubingattached to the pump.

Also disclosed herein is an electrical submersible pumping system (ESP)that in one example embodiment includes a motor section having a motor,a seal section in pressure communication with the motor, a pump sectionhaving a pump coupled with the motor, fins on an outer surface of themotor section, and a cover over the fins for shielding the fins fromdamage as the ESP is lowered into a wellbore. The cover is made from amaterial that detaches from the fins when the ESP is disposed in adesignated location in the wellbore. In one example embodiment the coveris made of wax, aluminum, zinc, beryllium, magnesium, alloys thereof, orcombinations thereof. The cover can be a single layer or multiplelayers. Optionally, the cover is made of a protective packingencapsulated in a protective layer; where the protective packing is asubstance such as particulate material, dissolvable powders, low meltingpoint metals and polymers or other hydrocarbon materials, such as lead,tin, bismuth, lithium, or alloys of, foams, particulates, sand, plaster,wax, or combinations thereof. In this embodiment, the outer layer isaluminum, zinc, beryllium, magnesium, alloys thereof, and combinationsthereof.

BRIEF DESCRIPTION OF DRAWINGS

Some of the features and benefits of the present invention having beenstated, others will become apparent as the description proceeds whentaken in conjunction with the accompanying drawings, in which:

FIG. 1 is a side partial sectional view of an example embodiment of anelectrical submersible pumping system (ESP) having cooling fins anddisposed in a wellbore.

FIG. 2 is an axial sectional view of the ESP of FIG. 1 showing aprotective layer over the fins.

FIG. 3 is an axial sectional view of the ESP of FIG. 1 having analternative protective covering over the fins that is encapsulated withan outer layer.

FIG. 4 is a side partial sectional view of the ESP of FIG. 1 having aprotective covering over the fin area and being lowered into a wellbore.

While the invention will be described in connection with the preferredembodiments, it will be understood that it is not intended to limit theinvention to that embodiment. On the contrary, it is intended to coverall alternatives, modifications, and equivalents, as may be includedwithin the spirit and scope of the invention as defined by the appendedclaims.

DETAILED DESCRIPTION OF INVENTION

The present invention will now be described more fully hereinafter withreference to the accompanying drawings in which embodiments of theinvention are shown. This invention may, however, be embodied in manydifferent forms and should not be construed as limited to theillustrated embodiments set forth herein; rather, these embodiments areprovided so that this disclosure will be through and complete, and willfully convey the scope of the invention to those skilled in the art.Like numbers refer to like elements throughout.

FIG. 1 illustrates an example embodiment of an electrical submersiblepumping system (ESP) 10 disposed in a subterranean wellbore 12; the ESPis used for pumping fluid 14 from the wellbore 12. The fluid 14 residesas connate fluid within a formation 16 shown adjacent the wellbore 12;the fluid 14 enters the wellbore 12 through perforations 18 in a casingstring 20 that lines the wellbore 12. The ESP 10 includes a motorsection 22 on its lower end having heat cooling fins 24 on its outersurface and extending generally axially along the length of the motorsection 22. The fins 24 provide for an increased heat transfer surfacearea from a motor 23 within the motor section 22 to fluid 14 that flowsover the housing of the motor section 22 from the perforations 18 andupward to a pump inlet 25. Also included with the ESP 10 is a sealsection 26 provided on an upper end of the motor section 22. The sealsection 26 localizes pressure within the ESP 10 with the pressureambient to the ESP 10. In one example, the seal section 26 includes aninternal bladder (not shown) that on one side is exposed to the ambientpressure and on the other side is dielectric fluid that makes its waybetween the seal section 26 and motor section 22. Also included with theESP 10 is a pump section 28 on which the pump inlets 25 are located aswell as a pump 29 that receives the fluid 14 after flowing through thepump inlets 25. The pump 29 is driven by the motor 23 by a shaft 30coupled between the motor 23 and pump 29. After becoming pressurized bythe pump 29, the fluid 14 exits the upper end of the pump section 28where it is then pumped to the surface through attached productiontubing 32.

In one embodiment, the fins 24 are relatively thin and easily damagedeven by slight impact by the ESP 10 against the casing 20. This isexacerbated in deviated portions of the well. Shown in FIG. 2 is asectional view of the motor section 22A illustrating an embodiment wherethe fins 24 are provided on an annular sleeve 34 shown circumscribingthe motor 23. In this embodiment, the sleeve 34 with fins 24 provideshousing for the motor 23 and is in contact with the cylindrical motorstators (not shown) inside the motor 23. Optionally, a thermal grease orfiller 36 can be provided in the annular space between the motor 23 andinner surface of the sleeve 34. Further illustrated in FIG. 2 is acovering over the fins 24 that is a protective packing 40 that extendsfrom the spaces between each of the adjacent fins 24 and past the outerterminal end of each fin 24 to protect against direct collisions. Theprotective packing 40 also provides support between the fins 24 therebyenhancing integrity of the fins 24.

The protective packing 40 can be applied over the fins 24 prior todeploying the ESP 10 within the wellbore 12 to guard the fins 24 fromdamage due to collisions or other contact between the ESP 10 and casing12. The protective packing 40 can be made from a material thatself-removes over time, such as through disintegration or dissolvingwhen in the wellbore. Example self-removal times range from a few hoursto 2-3 days. The disintegrating material may be one that quicklycorrodes and may contain aluminum, zinc, beryllium, magnesium, alloys ofthese materials, and combinations thereof. Optionally, the protectivepacking 40 may be a single or multi-layered structured material, such asaluminum with a less active material coupled directly to the fins 24,such as steel, or a more active alloy or pure layer, such as magnesiumcoupled with the aluminum. Additionally, the sleeve 34 can be formed byan extrusion process to facilitate manufacturing.

Referring now to FIG. 3, illustrated is a side sectional view of analternate embodiment of a motor section 22B. In this example, the sleeve34 with fins 24 is shown on the outer surface of the motor 23 along withthe layer of thermal grease or filler 36 between the motor 23 and sleeve34. However, an alternate protective covering over the fins 24 includesa protective packing 40A that is in contact with the fins and extendingfrom between adjacent fins and up above or past the terminal ends of thefins 24. Over the protective packing 40A is a protective layer 42 thatencapsulates the protective packing 40A in place over the fins 24. In analternative, the protective packing 40A is between the adjacent fins 24and the protective layer 42 contacts the terminal ends of the fins 24.In one example, the protective packing 40A may include plaster, sand, orsome other particulate matter. Once the protective layer 42 is removed,the protective packing 40A can fall away or erode, such as from thefluid 14 flowing past the fins 24. Additionally, the packing 40A and/orlayer 42 can be dissolved or disintegrated such as by a chemicalreaction or corrosion. Chemical and/or electrical current applicationcan accelerate the chemical reaction or corrosion. The protective layer42 may be formed from a dissolving or disintegrating material such asthat described above in reference to the protective layer 40 of FIG. 2.

FIG. 4 illustrates in a side partial sectional view an example of theESP 10A being lowered within a wellbore 12. In this example, the ESP 10Aincludes a protective packing 40 or optionally having a protective layer42 over the motor section 22A. As previously discussed, the presence ofthe protective packing 40 and/or protective layer 42 guards againstdamage or other degradation to the fins 24 while the ESP 10 is beinglowered within the wellbore 12. When at a designated location in thewellbore 12, wellbore conditions and/or the flow of fluid 14 removes theprotective packing and/or protective layer 42. By lowering the ESP 10 inthe wellbore 12 without damaging the fins 24, effective heat transfermay occur during pumping operations thereby cooling the motor 29 oncethe protective packing 40 and/or protective layer 42 is removed from theESP 10A. Also, the protective layer may allow for thinner fins which maybe more economical to produce. In an alternative embodiment, the ESP 10may be activated before the packing 40 or layer 42 is removed. In anexample, fluid flow from the ESP 10 may be used for removing the packing40 and/or layer 42.

It is to be understood that the invention is not limited to the exactdetails of construction, operation, exact materials, or embodimentsshown and described, as modifications and equivalents will be apparentto one skilled in the art. In the drawings and specification, there havebeen disclosed illustrative embodiments of the invention and, althoughspecific terms are employed, they are used in a generic and descriptivesense only and not for the purpose of limitation. For example, thepacking 40 and layer 42 can be made of a single layer or multiplelayers. Accordingly, the invention is therefore to be limited only bythe scope of the appended claims.

1. A method of cooling an electrical submersible pumping system (ESP) comprising: a. providing fins on an outer surface of the ESP; b. shielding the fins from damage by covering the fins with a protective layer of a self removing material; and c. deploying the ESP with the protective layer into a wellbore, so that when the ESP contacts a wall of the wellbore, the protective layer safeguards the fins from damage.
 2. The method of claim 1, wherein the material disintegrates when disposed in a wellbore and the fins conduct heat from within the ESP to fluid in the wellbore.
 3. The method of claim 1, wherein the material comprises a substance selected from the group consisting of wax, aluminum, zinc, beryllium, magnesium, alloys thereof, and combinations thereof.
 4. The method of claim 1, wherein the protective layer comprises a protective packing encapsulated with an outer layer.
 5. The method of claim 4, wherein the protective packing comprises a substance selected from the list consisting of particulate material, dissolvable powders, wax, sand, plaster, and combinations thereof.
 6. The method of claim 4, wherein the outer layer comprises a substance selected from the group consisting of aluminum, wax, zinc, beryllium, magnesium, alloys thereof, and combinations thereof.
 7. The method of claim 1, wherein the fins are disposed on a motor section of the ESP that contains a motor for driving a pump in the ESP.
 8. The method of claim 7, further comprising actuating the motor to drive the pump and pumping fluid from the wellbore into production tubing attached to the pump.
 9. An electrical submersible pumping system (ESP) comprising: a motor section having a motor; a seal section in pressure communication with the motor; a pump section having a pump coupled with the motor; fins on an outer surface of the motor section; and a cover over the fins for shielding the fins from damage as the ESP is lowered into a wellbore and for automatically detaching from the ESP when the ESP is disposed in a designated location in the wellbore.
 10. The ESP of claim 9, wherein the cover comprises a substance selected from the group consisting of aluminum, zinc, wax, beryllium, magnesium, alloys thereof, and combinations thereof.
 11. The ESP of claim 9, wherein the cover comprises a protective packing encapsulated in an outer layer.
 12. The ESP of claim 11, wherein the protective packing comprises a substance selected from the list consisting of particulate material, wax, sand, plaster, and combinations thereof.
 13. The ESP of claim 11, wherein the outer layer comprises a substance selected from the group consisting of aluminum, zinc, beryllium, magnesium, alloys thereof, and combinations thereof. 